Fire extinguishing composition



United States Patent 3,252,902 FIRE EXTINGUISHIN G COMPOSITION NorbertMevel, Antony, France, assignor to Societe dEtudes Chimiques pourlIndustrie et lAgriculture,

S.E.C.P.I.A., Paris, France No Drawing. Filed July 15, 1963, Ser. No.295,229 Claims priority, application France, Aug. 3, 1962,

905,978, Patent 1,337,470; Feb. 15, 1963, 924,940,

Patent 83,080; Apr. 4, 1963, 930,451, Patent 83,524

11 Claims. (Cl. 2522) This invention relates to fire extinguishingsolutions for use against fires of all kinds, e.g. dry fires, fires ofhydrocarbons and inflammable chemicals, and mixed fires, that is to say,fires of combustible solid substances (wood, paper, rags, etc.) soakedfor example with hydrocarbons or chemicals.

The extinguishing solutions disclosed in the present invention have alsothe advantage of being highly effective against extremely rebelliousfires such as those of carbon disulfide, mercaptans and other sulfurcompounds which were inextinguishable heretofore with the knownsolutions.

It is well known that many potassium salts have interestingextinguishing properties and may be used either in form of powder or inform of aqueous solutions to fight fires. A few organic acid salts suchas formate, oxalate and acetate figure among the potassium salts alreadyproposed. Both formate and oxalate although effective on some fires, arenot used in practice because when decomposed by heat, they result in theformation to toxic products (cyanides in the case of formate and carbonoxide in the case of oxalate). Also, under certain predeterminedconditions as disclosed in my concurrently filed U.S.'application, Ser.No. 295,213, highly concentrated potassium acetate aqueous solutionswill master fires difficult to extinguish such as those of hydrocarbonsand inflammable chemicals, but are not effective against fires of sulfurcompounds such as carbon disulfide and mercaptans.

The principal object of this invention, therefore, is to provide fireextinguishing solutions which are generally effective against all typesof fires, but are particularly effective against fires ofsulfur-containing materials.

Another object is to provide a method of extinguishing fires, using thefire extinguishing solution of this invention.

Upon further study of the specification and claims, other objects andadvantages of the present invention will become apparent.

It has now been found that an excellent extinguishing effect is obtainedon fires of all kinds as well as on rebellious fires of organic sulfurcompounds by using aqueous solutions containing a potassium salt ofpropionic, nbutyric, isobutyric or n-valeric acids or a mixture of thesesalts. These fire extinguishing solutions disclosed in the presentinvention can be employed in any usual type of apparatus for projectingor spraying water under gas pressure.

The effectiveness of these organic acid potassium salt solutions dependson both the nature of anion selected and the concentration of solutionused. It has been surprisingly observed that a practically equivalentextinguishing power is obtained with solutions having a lowerconcentration when the molecular weight of anion is higher. Forinstance, when dealing under the same conditions with fires of carbondisulfide and using solutions containing either about 500 g./l. ofpotassium propionate, 300 to 400 g./l. of potassium n-butyrate, or 100to 200 g./l. of potassium n-valerate, theresults obtained are excellentand practically equivalent. Substantially more dilute solutions aresuitable to extinguish hydrocarbon fires or fires of very' inflammablechemicals difficult to fight but, how- Patented May 24, 1966 ever, notso rebellious as those of sulfur compounds. For example, with solutionscontaining 50 g./l. of potassium n-valerate, or 50 to g./l. of potassiumn-butyrate, or 100 to 200 g./l. of potassium propionate used to fightgasoline fires, times for extinction are very short and practically thesame in each case.

However, it has been observed that for the three abovementioned salts(propionate, n-butyrate and n-valerate) although the extinguishingeffect increases with the molecular weight of the anion, the nature ofthe anion itself seems also to have an influence: indeed, the effect ofpotassium isobutyrate is not quite so good as that of nbutyrate. Thedifference is more perceptible when the fire is more difficult toextinguish and when more dilute solutions are used. Thus, laboratorytests have shown that a gasoline fire of given area is extinguished in 3seconds with a solution of 50 g./l. of n-butyrate while 6 seconds arenecessary with a solution of same isobutyrate concentration; with asolution containing 100 g./l. of either salt the same fire isextinguished in less than one second.

It has further been found that beyond a certain concentration of each ofthe salts mentioned above, the ex tinguishing effect tends to diminish;hence, it is advisable to use solutions containing less than 600 g./l.of propionate or butyrates and less than 400 g./l. of n-valerate. Whenusing a mixture of salts the total concentration of the various salts isto be considered.

With respect to the minimum concentration of the salts, obviously it isintended to employ an operable amount, i.e. sufficient to result in atleast a finite fire extinguishing activity. For precautionary purposes,however, it is preferable to employ minimum concentrations of about 50g./l. propionate, 25-30 g./l. butyrates and 25 30 g./l. n-valerate.

It has also been unexpectedly found that by adding to theseextinguishing solutions a small quantity of a lower aliphatic alcohol,particularly a lower alkanol, the extinguishing effect is considerablyincreased for the same potassium salt concentration.

It has been observed that such an addition of alcohol reducessubstantially the quantity ofextinguishing solution required to put outa hydrocarbon fire of given area. Field tests were performed on fires ofessence F (mineral spirit having a boiling range from 100 to C. undernormal pressure) of 0.50 m. area with a spraying apparatus of determinedcapacity which projects the solution under specific conditions ofpressure and flow rate. When the extinguisher is filled with potassiumpropionate, butyrates or n-valerate solutions without any addition ofalcohol, the apparatus can be used for one extinction only: after thefirst extinguishing operation it is empty or contains a too smallquantity of solution to perform a second operation. But if, for example,2% of methanol are added to these solutions 2 to 4 extinguishingoperations can be effected with the same charge.

To fight hydrocarbon fires the quantity of alcohol added to theextinguishing solutions disclosed in the present invention should notexceed about 5% by weight of solution, for beyond this amount theextinguishing effect decreases. In practice, a quantity of from 1 to 2%of alcohol is preferred since it gives excellent results on hydrocarbonfires with solutions containing either 100 to 200 g./l. of potassiumpropionate, 50 to 100 g./l. potassium butyrates, or about 50 g./l. ofpotassium n-valerate. The above-given figures for potassium saltconcentrations are, however, not to be considered as uppermost operablelimits; more concentrated solutions are also suitable but obviously itis more economical to work with as dilute solutions as possible.

According to the present invention, aliphatic alcohols having ahydrocarbon radical containing from 1 to 3 carbon atoms, that is to say,methanol. ethanol, nand isopropanol are preferably used. These alcoholsneed not be pure; inexpensive commercial products and mixtures of sameare perfectly suitable. In particular, the addition of denaturedalcohols which are products of very low cost gives excellent results.

When fighting fires of carbon disulfide and other sulfur compounds, ithas been observed that addition of isopropanol, in particular, to thesolutions has an especially favorable effect. The times for extinctionare notably shorter for the same potassium salt concentration and therisk of re-flashing is reduced or even suppressed. Moreover, such anaddition of isopropanol gives an equivalent extinguishing etfect withsolutions of lower potassium salt concentration.

Thus, for example, laboratory tests performed under the same conditionshave shown that the time for the extinction of a carbon disulfide firecan be reduced from 11 to seconds (S-test average) by adding by weightof isopropanol to a solution containing 500 g./l. of potassiumn-butyrate. On the other hand, with a solution containing 50 g./l. ofpotassium n-butyrate to which 10% by weight of isopropanol had beenadded, it took 21 seconds to extinguish a carbon disulfide fire, whereaswith a solution 4 times more concentrated (200 g./l. of nbutyrate) butcontaining no isopropanol, extinction is uncertain (2 extinctions out of5 tests).

The quantity of isopropanol added to extinguishing solutions forfighting fires of sulfur compounds should not exceed by weight ofsolution, for beyond this amount isopropanol being easily inflammable,the solutions themselves may catch fire. As a general rule, a quantityfrom about 5 to 10% of isopropanol is enough to give excellent resultseven when using less concentrated potassium salt solutions; thus, withthe above-mentioned amounts of isopropanol it is economical to usesolutions containing either 300 to 400 g./l. potassium propionate, 200to 300 g./l. of potassium n-butyrate, or 50 to 150 g./l. of potassiumn-valerate.

When fighting mixed fires such as wood, paper, rags, etc., soaked withinflammable liquids, tetrapotassium pyrophosphate may be added to thesolutions disclosed in the present invention, for this salt will give tothe combustible solid substances sprayed with extinguishing liquid suchfireproof qualities that the risk of re-fiashing is greatly reduced oreven avoided. About 100 to 200 g./l. of tetrapotassium phyrophosphate isgenerally enough to give satisfactory results.

The extinguishing solutions disclosed in the present invention can besprayed onto the fire by means of any usual type of apparatus withoutany risk of the spraying nozzles becoming choked, for within the limitsof concentration given above, the quantity of each salt containedtherein is sufficiently far from saturation point so that the salts donot tend to precipitate during the spraying operation.

A small quantity of wetting agent may be added to the solutionsdisclosed in the present invention as is usually done for water andvarious known salt solutions. Whereas such an addition does not alterthe specific effectiveness of said solutions, it can neverthelessimprove the extinguishing effect by making the liquid easier to dispersethus facilitating the spraying operation. As a matter of fact, the useof a wetting agent depends mostly on the type of spraying apparatusselected. It is quite obvious that the wetting agent used must becompatible with the salt dissolved. Thus, for example, a wetting agentof the oxyethylenic alkylphenol type, or a phosphate ester of non-ioniccompounds, or quaternary ammonium salts may be used, preferably inquantity not exceeding 2% by weight of solution, specific examples ofsuch wetting agents being compounds of formula R R C H O(CH CH O),,Hwhere n is 6 to 15, R is H or CH and R an alkyl moiety having 8 or 9carbon atoms, a phosphate ester of a polyoxyethylenic alkyl-(orarylalkyl) phenol, or an alkyl dimethyl benzyl ammonium chloride, thealkyl moiety having 12 to 18 carbon atoms.

The extinguishing solutions disclosed in the present invention haveanother outstanding advantage: their freezing point is very low. Thus,the freezing point of a solution containing 500 g./l. of potassiumpropionate is below 60 C. and that of n-butyrate solutions containingfrom 200 to 400 g./l. ranges between 8 and 40 C. It is thereforepossible to choose the most suitable composition according to climaticconditions in the place where the solutions will be stored.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the specification and claims in any way whatsoever.

Example 1 Systematic laboratory tests were performed on carbon disulfidefires with an apparatus giving a representative and homothetic pictureof field tests, said field tests being carried out in a round panmeasuring 1 m. diameter and 0.20 m. high, arranged so that the bottom ishorizontal. Testing conditions in laboratory are, however, even morestringent as compared to those of field tests. This is the case becausein the laboratory equipment, the angle under which the fire is attackedby the solution spray is such that it creates an important turbulence inthe burning substance thereby preventing the formation of a protectivesalt layer on the fire. Furthermore, the solution being sprayed by meansof air, the combustion is activated. In this manner, while laboratorytests serve to determine the optimal concentrations of solutions, theactual limits of utilization are larger than those revealed in thelaboratory.

Aqueous solutions containing from 50 to 700 g./l. of potassiumn-butyrate were tested in laboratory under the following conditions:carbon disulfide was ignited and left to burn for 30 seconds, then thesolution was projected onto the fire and time for extinction measured.The substance was re-ignited and after 15 seconds of combustion thesolution was again projected onto the fire and time for extinctionmeasured. The same operation was carried out ten times following. I

With solutions containing only 200 g./l. of n-butyrate, the fire wasextinguished only twice out of 5 tests; average time for extinction forthe two successful tests being 49 seconds in the case of first ignitionand 2 to 7 seconds for the following re-ignitions.

The table hereunder shows the S-test average time required forextinction when using solutions containing respectively 300, 400 and 500g./l. of n-butyrate. The first column of the table gives theextinguishing time for tht first ignition (Ign) and the followingcolumns numbered from 1 to 10 give the extinguishing times for thefollowing reignitions, the time being expressed in seconds.

Concentration of the solution Ign 1 2 3 4 5 6 7 8 9 10 Example 2 10liters of carbon disulfide were poured into a round pan measuring 0.80m. diameter and 0.20 m. high placed so that the bottom is horizontal,the substance was ignited and left to burn for 1 minute; then a solutioncontaining 500 g./l. of potassium propionate and 2% by weight of awetting agent of quaternary ammonium salt type was sprayed onto thefire.

The time required for complete extinction was 10 seconds- For the threefollowing re-ignitions, the fire being left to burn for 30 seconds, ittook respectively 10, 3 and 3 seconds to obtain complete extinction.

When 10% of isopropanol were added to the solution disclosed hereabove,the time for extinction was 3 seconds for first ignition, 2 seconds fornext re-ignition, but after that the carbon disulfide left in the pancannot be re-ignited.

' Example 3 Example 2 was repeated, potassium propionate being replacedby potassium n-valerate (125 g./l. of solution).

Time for first extinction was 9 seconds and for the next three:respectively 11, 2 and 3 seconds.

With addition of 5% of isopropanol to the solution disclosed hereabove,the time for first extinction was 5 seconds and 3 seconds for the next;re-ignition of the 7 carbon disulfide left in the pan was then no morepossible.

Example 4 Same operating conditions as for Example 2.

Three series of tests were performed with solutions containing 500 and300 g./l. of potassium n-butyrate (B), a wetting agent (WA) of thequaternary ammonium type, and (for 2 series of tests) some isopropanol(I). The table hereunder illustrates the average results obtained foreach series of tests, s representing seconds.

Ignition Re-ig- Time Time nition for Solution for Numextincextincbertion, 5 tion, 5

500 g./l. B plus 2% WA 30 5 10 to 500 g./l. B plus 2% WA plus 10% I 2 15 300 g./l. B plus 1% WA plus 10% I 2 1 2 With solutions containingisopropanol, re-ignition was impossible after the second extinction.

Example 5 Time for extinction (Re-ignition: 8)

Time for extinc- Solution used, g./l. tion (ignition) n-Valerate 50 2 sn-Valerate 100 0.5 s n-Butyrate 100-... From 0.5 to l s.. n-Butyrate 503 s grom 0.5 to 1 s From 1 to 5 s. 0.5 s.

From 0.5 to 1 s. From 1.5 to 3 s.

From 0.5 to 1 s. From 2 to 3 s.

Isobutyrate 100 Propionate 100.

Example 6 Two series of tests were performed under the followingconditions:

10 liters of-essence F (mineral spirit having a boiling range from to C.under normal pressure) were poured into .a round pan measuring 0.80 m.diameter and 0.20 m. high, ignited and left to burn for one minute. Thefire was then attacked using an apparatus containing 9 liters ofsolution and projecting it onto the fire under the same conditions ofpressure and flow rate for each case.

A first series of tests was performed with a solution containing 200g./l. of potassium propionate. The average time for extinction was 30seconds. It was not possible to effect two extinctions running withoutrefilling the apparatus.

A second series of tests was performed with a solution of same potassiumpropionate concentration but to which 2% of isopropanol by weight hadbeen added. The average time for extinction was 5 to 6 seconds. 'Out of10 tests, it was possible to effect 5 times 2 extinctions with one samecharge, twice 3 extinctions and 3 times 4 extinctions.

Example 7 Same operating conditions as for Example 6, but essence F wasreplaced by motor gasoline having a density not exceeding 0.760, a finalpoint of distillation below 205 C., and an octane number of 92.

A solution containing 200 g./l. of potassium propionate and 2% ofdenatured alcohol by weight was used.

With each charge of the apparatus at least 3 extinguishing operationswere effected in each case. The average time for extinction was 3 to 4seconds.

Example 8 Ten liters of carbon disulfide were poured-into a round panmeasuring 0.80 m. diameter and 0.20 m. high placed so that the bottom ishorizontal, then some old rags and pieces of wood were .piled on top,ignited and leftto burn for 2 minutes until the Whole stake was fiercelyablaze.

A solution containing 300 g./l. of potassium n-butylrate, 100 g./l. oftetrapotassium pyrophosphate, 10% of isopropanol by weight and 1% of awetting agent (oxethylenic long chain amine).

Time for extinction was 3 seconds. After re-ignition and 30 seconds ofcombustion, second extinction took 2 seconds. Re-ignition of the carbondisulfide left in the pan was then no more possible.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scopethereof, can make Various changes andmodifications of the invention to adapt it to various usages andconditions. Consequently, such changes and modifications are properly,equitably, and intended to be, within the full range of equivalence ofthe following claims.

What is claimed is:

1. A method of extinguishing a hydrocarbon fire, which method comprises.contacting the source of the fire with an aqueous solution of less thanabout 5% by weight of an aliphatic alcohol of 1-3 carbon atoms a. saltselected from the group consisting of potassium propionate, potassiumn-butyrate, potassium isobutyrate, potassium nvalerate, and mixturesthereof, said salt being present in an amount sufiicient to result in atleast a finite fire extinguishing activity.

2. A method of extinguishing a fire of an organic sulfur compound, whichmethod comprises contacting the source of the fire with an aqueoussolution of less than about 20% by weight of isopropanol and a saltselected from the group consisting of potassium propionate, potassiumn-butyrate, potassium isobutyrate, potassium n-valerate, and mixturesthereof, said salt being present in an amount sufiicient to result in atleast a finite fire extinguishing activity.

3. The process of claim 1, wherein the aliphatic a1- cohol is selectedfrom the group consisting of methanol, ethanol, nand isopropanol.

4. A fire extinguishing aqueous solution for fighting fires ofhydrocarbons which on the basis of a liter of solution comprises apotassium salt selected from the group consisting of potassiumpropionate in a concentration of about 100-200 g./l., potassium butyratein a concentration of about 50-100 g./l., and potassium nvalerate in aconcentration of about 50 g./1., and about 12% by weight of solution ofan aliphatic alcohol of 1-3 carbon atoms, and sufficient Water to make aliter of solution.

5. The solution of claim 4, wherein the aliphatic alcohol is selectedfrom the group consisting of methanol, ethanol, n-propanol, isopropanol,and mixtures thereof.

6. The solution of claim 4, further comprising tetrapotas'siumpyrophosphate.

7. The solution of claim 6, further comprising a wetting agentcompatible with the potassium salt.

8. An aqueous solution for extinguishing fires of organic sulfurcompounds, which on the basis of a liter of solution comprises less thanabout 20% by weight of isopropanol, and a potassium salt selected fromthe group consisting of potassium propionate in a concentration of about300-400 g./l., potassium n-butyrate in a concentration of about 200300g./l., and potassium n-valerate in a concentration of about -150 g./l.and sufficient Water to make a liter of solution.

9. The solution of claim 8, wherein the isopropanol concentration is510% by weight of the solution.

10. The solution of claim 9, further comprising tetrapotassiumpyrophosph ate.

11. The solution of claim 10, further comprising a wetting agentcompatible with said potassium salt.

References Cited by the Examiner UNITED STATES PATENTS 9/1946 Craig etal. 260540 XR 3/1959 Jackson et al. 10615 OTHER REFERENCES JULIUSGREENWALD, Primary Examiner.

M. WEINBLATT, Assistant Examiner.

2. A FIRE EXTINGUISHING AQUEOUS SOLUTION FOR FIGHTING FIRES OFHYDROCARBONS WHICH ON THE BASIS OF A LITER OF SOLUTION COMPRISES APOTASSIUM SALT SELECTED FRO THE GROUP CONSISTING OF POTASSIUM PROPIONATEIN A CONCENTRATION OF ABOUT 100-200 G./L., POTASSIUM BUTYRATE IN ACONCENTRATION OF ABOUT 50-100 G./L., AND POTASSIUM N-VALERATE IN ACONCENTRATION OF ABOUT 50 G./L., AND ABOUT 1-2% BY WEIGHT OF SOLUTION OFAN ALIPHATIC ALCOHOL OF 1-3 CARBON ATOMS, AND SUFFICIENT WATER TO MAKE ALITER OF SOLUTION.